An embodiment of a feedback control method and unit of a servo controlled system which acts on the environment surrounding a user for adjusting at least one feature of the environment which affects the psychophysical state of the user; the control unit has: a memory device in which there is stored a desired optimal value or a range of desired optimal values of a psychophysical feedback parameter of the user correlated with the perception that the user has of the feature of the environment adjusted by the servo controlled system; an estimation device for cyclically estimating a real value of the psychophysical feedback parameter of the user by means of at least one measurement performed directly on the user; and a driving device for cyclically driving the servo controlled system for seeking the optimal desired value of the psychophysical feedback parameter.